I don't really know were to post this, but a few weeks ago I was in a bad accident with my horse, but it wasn't her fault. Anyways, whenever I ride her I get really tense and nervous, I can't sit deep in my seat and I can feel my heart beating faster. I can't help it, and it makes her very nervous too, she sidesteps and she also gets tense. I don't get nervous with any of my other horses. It feels like every time I ride her she is going to do the same thing. I really want to stay calm on her, and boost my confidence.
What can I do to boost my confidence and and calm both of us?